Imaging lens

ABSTRACT

There is provided an imaging lens with excellent optical characteristics while satisfying demand of low-profileness and low F-number. An imaging lens comprises, in order from an object side to an image side, a first lens with positive refractive power formed in a biconvex shape having an object-side surface and an image-side surface being convex in a paraxial region, a second lens with negative refractive power in a paraxial region, a third lens with the negative refractive power in a paraxial region, a fourth lens with the negative refractive power in a paraxial region, and a fifth lens with the positive refractive power having an image-side surface being convex in a paraxial region, and predetermined conditional expressions are satisfied.

The present application is based on and claims priority of a Japanesepatent application No. 2019-059619 filed on Mar. 27, 2019, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an imaging lens which forms an image ofan object on a solid-state image sensor such as a CCD sensor or a C-MOSsensor used in an imaging device.

Description of the Related Art

In recent years, it becomes common that camera function is mounted invarious products, such as home appliances, information terminalequipment, automobiles, and the like. Development of products with thecamera function will be made accordingly.

The imaging lens mounted in such equipment is required to be compact andto have high-resolution performance.

As a conventional imaging lens aiming high performance, for example, theimaging lens disclosed in the following Patent Document 1 has beenknown.

Patent Document 1 (CN105607232A) discloses an imaging lens comprising,in order from an object side, a first lens having positive refractivepower and a convex object-side surface, a second lens having refractivepower and a convex image-side surface, a third lens having negativerefractive power, a fourth lens having negative refractive power and anaspheric image-side surface, and a fifth lens having refractive powerand a convex image-side surface, wherein a relationship between a totaltrack length and a focal length of an overall optical system satisfies acertain condition.

SUMMARY OF THE INVENTION

However, in lens configurations disclosed in the Patent Document 1, whena low profile and a low F-number are to be realized, it is verydifficult to correct aberrations at a peripheral area, and excellentoptical performance can not be obtained.

The present invention has been made in view of the above-describedproblems, and an object of the present invention is to provide animaging lens with high resolution which satisfies demand of the lowprofile and the low F-number in well balance and excellently correctsaberrations.

Regarding terms used in the present invention, “a convex surface” or “aconcave surface” of lens surfaces implies that a shape of the lenssurface in a paraxial region (near the optical axis). “Refractive power”implies the refractive power in the paraxial region. “A pole point”implies an off-axial point on an aspheric surface at which a tangentialplane intersects the optical axis perpendicularly. “A total tracklength” is defined as a distance along the optical axis from anobject-side surface of an optical element located closest to the objectto an image plane. “The total track length” and “a back focus” is adistance obtained when thickness of an IR cut filter or a cover glasswhich may be arranged between the imaging lens and the image plane isconverted into an air-converted distance.

An imaging lens according to the present invention comprises, in orderfrom an object side to an image side, a first lens with positiverefractive power formed in a biconvex shape having an object-sidesurface and an image-side surface being convex in a paraxial region, asecond lens with negative refractive power in a paraxial region, a thirdlens with the negative refractive power in a paraxial region, a fourthlens with the negative refractive power in a paraxial region, and afifth lens with the positive refractive power having an image-sidesurface being convex in a paraxial region.

According to the imaging lens having the above-described configuration,the first lens achieves reduction in a profile by strengthening therefractive power. Furthermore, the first lens is formed in the biconvexshape having the object-side surface and the image-side surface beingconvex in the paraxial region; therefore, a curvature is suppressed frombeing large, and sensitivity to a manufacturing error can be reduced.

The second lens properly corrects chromatic aberration, sphericalaberration, coma aberration, astigmatism and distortion.

The third lens properly corrects the coma aberration, the astigmatismand the distortion.

The fourth lens properly corrects the chromatic aberration, theastigmatism, field curvature and the distortion.

The fifth lens maintains a low profile and properly corrects thespherical aberration, the astigmatism, the field curvature and thedistortion. An image-side surface of the fifth lens is convex in theparaxial region and a light ray incident angle to an image sensor can beproperly controlled. As a result, a lens diameter of the fifth lens canbe reduced and reduction in the diameter of the imaging lens can beachieved.

According to the imaging lens having the above-described configuration,it is preferable that an object-side surface of the second lens isconvex in the paraxial region.

When the object-side surface of the second lens is convex in theparaxial region, the spherical aberration, the coma aberration, theastigmatism and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that an image-side surface of the second lens isconcave in the paraxial region.

When the image-side surface of the second lens is concave in theparaxial region, the coma aberration, the astigmatism and the distortioncan be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that an image-side surface of the third lens is concavein the paraxial region.

When the image-side surface of the third lens is concave in the paraxialregion, the coma aberration, the astigmatism and the distortion can beproperly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (1) issatisfied:10.00<vd2<30.00  (1)

where

vd2: an abbe number at d-ray of the second lens.

The conditional expression (1) defines an appropriate range of the abbenumber at d-ray of the second lens. By satisfying the conditionalexpression (1), the chromatic aberration can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (2) issatisfied:0.10<|r5|/f<0.90  (2)

where

r5: a paraxial curvature radius of an object-side surface of the thirdlens, and

f: a focal length of the overall optical system of the imaging lens.

The conditional expression (2) defines an appropriate range of theparaxial curvature radius of the object-side surface of the third lens.By satisfying the conditional expression (2), the coma aberration andthe distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (3) issatisfied:20.50<T3/T4<49.00  (3)

where

T3: a distance along the optical axis from an image-side surface of thethird lens to an object-side surface of the fourth lens, and

T4: a distance along the optical axis from an image-side surface of thefourth lens to an object-side surface of the fifth lens.

The conditional expression (3) defines an appropriate range of arelationship between the distance along the optical axis from theimage-side surface of the third lens to the object-side surface of thefourth lens and the distance along the optical axis from the image-sidesurface of the fourth lens to the object-side surface of the fifth lens.By satisfying the conditional expression (3), the fourth lens isarranged at an optimum position, and aberration correction function ofthe lens becomes more effective. As a result, reduction in the profilecan be achieved and the astigmatism and the distortion can be properlycorrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (4) issatisfied:2.00<r8/f<35.00  (4)

where

r8: a paraxial curvature radius of an image-side surface of the fourthlens, and

f: a focal length of the overall optical system of the imaging lens.

The conditional expression (4) defines an appropriate range of theparaxial curvature radius of the image-side surface of the fourth lens.When a value is below the upper limit of the conditional expression (4),the distortion can be properly corrected. On the other hand, when thevalue is above the lower limit of the conditional expression (4), theastigmatism and the field curvature can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (5) issatisfied:−1.40<r10/f5<−0.40  (5)

where

r10: a paraxial curvature radius of an image-side surface of the fifthlens, and

f5: a focal length of the fifth lens.

The conditional expression (5) defines an appropriate range of arelationship between the paraxial curvature radius of the image-sidesurface of the fifth lens and the focal length of the fifth lens. Bysatisfying the conditional expression (5), refractive power of theimage-side surface of the fifth lens is suppressed from being excessive,and positive refractive power of the fifth lens becomes appropriate. Asa result, reduction in the profile can be achieved, and the astigmatism,the field curvature and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (6) issatisfied:−20.00<f2/T2<−5.50  (6)

where

f2: a focal length of the second lens, and

T2: a distance along the optical axis from an image-side surface of thesecond lens to an object-side surface of the third lens.

The conditional expression (6) defines an appropriate range of arelationship between the focal length of the second lens and thedistance along the optical axis from the image-side surface of thesecond lens to the object-side surface of the third lens. By satisfyingthe conditional expression (6), refractive power of the second lens canbe maintained, and the distance along the optical axis from theimage-side surface of the second lens to the object-side surface of thethird lens becomes appropriate. As a result, reduction in the profilecan be achieved, and the chromatic aberration, the coma aberration, theastigmatism and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (7) issatisfied:36.00<vd4<77.00  (7)

where

vd4: an abbe number at d-ray of the fourth lens.

The conditional expression (7) defines an appropriate range of the abbenumber at d-ray of the fourth lens. By satisfying the conditionalexpression (7), the chromatic aberration can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (8) issatisfied:0.30<(T4/f)×100<1.20  (8)

where

T4: a distance along the optical axis from an image-side surface of thefourth lens to an object-side surface of the fifth lens, and

f: a focal length of the overall optical system of the imaging lens.

The conditional expression (8) defines an appropriate range of thedistance along the optical axis between the fourth lens and the fifthlens. By satisfying the conditional expression (8), reduction in theprofile can be achieved, and the astigmatism and the distortion can beproperly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (9) issatisfied:−16.50<r2/f<−2.00  (9)

where

r2: a paraxial curvature radius of an image-side surface of the firstlens, and

f: a focal length of the overall optical system of the imaging lens.

The conditional expression (9) defines an appropriate range of theparaxial curvature radius of the image-side surface of the first lens.By satisfying the conditional expression (9), the coma aberration, theastigmatism and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (10) issatisfied:0.45<r4/|r5|<2.00  (10)

where

r4: a paraxial curvature radius of an image-side surface of the secondlens, and

r5: a paraxial curvature radius of an object-side surface of the thirdlens.

The conditional expression (10) defines an appropriate range of arelationship between the paraxial curvature radius of the image-sidesurface of the second lens and the paraxial curvature radius of theobject-side surface of the third lens. By satisfying the conditionalexpression (10), refractive powers of the image-side surface of thesecond lens and the object-side surface of the third lens can beappropriately balanced. As a result, the chromatic aberration, the comaaberration, the astigmatism and the distortion can be properlycorrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (11) issatisfied:4.00<|r5|/D3<30.00  (11)

where

r5: a paraxial curvature radius of an object-side surface of the thirdlens, and

D3: a thickness along the optical axis of the third lens.

The conditional expression (11) defines an appropriate range of arelationship between the paraxial curvature radius of the object-sidesurface of the third lens and the thickness along the optical axis ofthe third lens. By satisfying the conditional expression (11),refractive power of the object-side surface of the third lens can bemaintained, and the thickness along the optical axis of the third lenscan be secured. As a result, the astigmatism and the distortion can besuppressed and formability of the third lens can be excellent.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (12) issatisfied:−3.50<r7/T3<−0.50  (12)

where

r7: a paraxial curvature radius of an object-side surface of the fourthlens, and

T3: a distance along the optical axis from an image-side surface of thethird lens to an object-side surface of the fourth lens.

The conditional expression (12) defines an appropriate range of arelationship between the paraxial curvature radius of the object-sidesurface of the fourth lens and the distance along the optical axis fromthe image-side surface of the third lens to the object-side surface ofthe fourth lens. By satisfying the conditional expression (12),reduction in the profile can be achieved, a light ray incident angle tothe object-side surface of the fourth lens can be properly controlled,and the astigmatism and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (13) issatisfied:2.00<|r9|/f  (13)

where

r9: a paraxial curvature radius of an object-side surface of the fifthlens, and

f: a focal length of the overall optical system of the imaging lens.

The conditional expression (13) defines an appropriate range of theparaxial curvature radius of the object-side surface of the fifth lens.By satisfying the conditional expression (13), the astigmatism, thefield curvature and the distortion can be properly corrected.

According to the imaging lens having the above-described configuration,it is preferable that the following conditional expression (14) issatisfied:0.10<T2/T3<0.90  (14)

where

T2: a distance along the optical axis from an image-side surface of thesecond lens to an object-side surface of the third lens, and

T3: a distance along the optical axis from an image-side surface of thethird lens to an object-side surface of the fourth lens.

The conditional expression (14) defines an appropriate range of arelationship between the distance along the optical axis from theimage-side surface of the second lens to the object-side surface of thethird lens and the distance along the optical axis from the image-sidesurface of the third lens to the object-side surface of the fourth lens.By satisfying the conditional expression (14), the third lens isarranged at an optimum position, and the distortion can be properlycorrected.

Effect of Invention

According to the present invention, there can be provided an imaginglens with high resolution which satisfies demand of the low profile andthe low F-number in well balance, and properly corrects aberrations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an imaging lens in Example 1according to the present invention;

FIG. 2 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 1 according to the present invention;

FIG. 3 is a schematic view showing an imaging lens in Example 2according to the present invention;

FIG. 4 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 2 according to the present invention;

FIG. 5 is a schematic view showing an imaging lens in Example 3according to the present invention;

FIG. 6 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 3 according to the present invention;

FIG. 7 is a schematic view showing an imaging lens in Example 4according to the present invention;

FIG. 8 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 4 according to the present invention;

FIG. 9 is a schematic view showing an imaging lens in Example 5according to the present invention; and

FIG. 10 shows spherical aberration, astigmatism, and distortion of theimaging lens in Example 5 according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the preferred embodiments of the present invention will bedescribed in detail referring to the accompanying drawings.

FIGS. 1, 3, 5, 7 and 9 are schematic views of the imaging lenses inExamples 1 to 5 according to the embodiments of the present invention,respectively.

An imaging lens according to the present invention comprises, in orderfrom an object side to an image side, a first lens L1 with positiverefractive power formed in a biconvex shape having an object-sidesurface and an image-side surface being convex in a paraxial region, asecond lens L2 with negative refractive power in a paraxial region, athird lens L3 with the negative refractive power in a paraxial region, afourth lens L4 with the negative refractive power in a paraxial region,and a fifth lens L5 with the positive refractive power having animage-side surface being convex in a paraxial region.

A filter IR such as an IR cut filter or a cover glass is arrangedbetween the fifth lens L5 and an image plane IMG (namely, the imageplane of an image sensor). The filter IR is omissible.

An aperture stop ST is arranged between the third lens L3 and the fourthlens L4, and downsizing in a diameter direction is facilitated. Theaperture stop ST may be arranged on the object side of the first lens L1as in the Examples 3, 4 and 5 as shown in FIGS. 5, 7 and 9 . In thiscase, correction of aberrations and control of an incident angle of thelight ray of high image height to the image sensor can be facilitated.

The first lens L1 has the positive refractive power and is formed in thebiconvex shape having the convex object-side surface and the conveximage-side surface in a paraxial region (near the optical axis X).Therefore, reduction in the profile can be achieved by positiverefractive power of both sides. The both sides are convex; therefore, acurvature is suppressed from being large, and sensitivity to amanufacturing error can be reduced.

The second lens L2 has the negative refractive power and is formed in ameniscus shape having an object-side surface being convex and animage-side surface being concave in a paraxial region (near the opticalaxis X). Therefore, chromatic aberration, spherical aberration, comaaberration, astigmatism and distortion are properly corrected.

The third lens L3 has the negative refractive power and is formed in themeniscus shape having an object-side surface being convex and animage-side surface being concave in a paraxial region (near the opticalaxis X). Therefore, the coma aberration, the astigmatism and thedistortion are properly corrected.

The third lens L3 may be formed in a biconcave shape having theobject-side surface and the image-side surface being concave in theparaxial region as in the Examples 3, 4 and 5 as shown in FIGS. 5, 7 and9 . This case is favorable for correction of the chromatic aberration bythe negative refractive power of the both sides.

The fourth lens L4 has the negative refractive power and is formed inthe biconcave shape having the object-side surface and the image-sidesurface being concave in the paraxial region. Therefore, the chromaticaberration, the astigmatism, the field curvature and the distortion areproperly corrected.

The fifth lens L5 has the positive refractive power and is formed in thebiconvex shape having the object-side surface and the image-side surfacebeing convex in the paraxial region. Therefore, reduction in the profileis achieved, and the spherical aberration, the astigmatism, the fieldcurvature and the distortion are properly corrected. Furthermore, theimage-side surface of the fifth lens L5 is convex in the paraxialregion; therefore, a light ray incident angle to the image sensor can beappropriately controlled. As a result, a lens diameter of the fifth lensL5 can be reduced and reduction in the diameter of the imaging lens canbe achieved.

The fifth lens L5 may be formed in the meniscus shape having theobject-side surface being concave and the image-side surface beingconvex in the paraxial region as in the Example 2 as shown in FIG. 3 .In this case, a light ray incident angle to the fifth lens L5 can beappropriately controlled, and the distortion can be properly corrected.

Regarding the imaging lens according to the present embodiments, it ispreferable that all lenses of the first lens L1 to the fifth lens L5 aresingle lenses. Configuration only with the single lenses can frequentlyuse the aspheric surfaces. In the present embodiments, all lens surfacesare formed as appropriate aspheric surfaces, and the aberrations arefavorably corrected. Furthermore, in comparison with a case in which acemented lens is used, workload is reduced, and manufacturing in lowcost becomes possible.

Furthermore, the imaging lens according to the present embodiments makesmanufacturing facilitated by using a plastic material for all of thelenses, and mass production in a low cost can be realized.

The material applied to the lens is not limited to the plastic material.By using glass material, further high performance may be aimed. It ispreferable that all of lens-surfaces are formed as aspheric surfaces,however, spherical surfaces which are easy to be manufactured may beadopted in accordance with required performance.

The imaging lens according to the present embodiments shows preferableeffects by satisfying the following conditional expressions (1) to (14).10.00<vd2<30.00  (1)0.10<|r5|/f<0.90  (2)20.50<T3/T4<49.00  (3)2.00<r8/f<35.00  (4)−1.40<r10/f5<−0.40  (5)−20.00<f2/T2<−5.50  (6)36.00<vd4<77.00  (7)0.30<(T4/f)×100<1.20  (8)−16.50<r2/f<−2.00  (9)0.45<r4/|r5|<2.00  (10)4.00<|r5|/D3<30.00  (11)−3.50<r7/T3<−0.50  (12)2.00<|r9|/f  (13)0.10<T2/T3<0.90  (14)

where

vd2: an abbe number at d-ray of the second lens L2,

vd4: an abbe number at d-ray of the fourth lens L4,

D3: a thickness along the optical axis X of the third lens L3,

T2: a distance along the optical axis X from an image-side surface ofthe second lens L2 to an object-side surface of the third lens L3,

T3: a distance along the optical axis X from an image-side surface ofthe third lens L3 to an object-side surface of the fourth lens L4,

T4: a distance along the optical axis X from an image-side surface ofthe fourth lens L4 to an object-side surface of the fifth lens L5,

f: a focal length of the overall optical system of the imaging lens,

f2: a focal length of the second lens L2,

f5: a focal length of the fifth lens L5,

r2: a paraxial curvature radius of an image-side surface of the firstlens L1,

r4: a paraxial curvature radius of an image-side surface of the secondlens L2,

r5: a paraxial curvature radius of an object-side surface of the thirdlens L3,

r7: a paraxial curvature radius of an object-side surface of the fourthlens L4,

r8: a paraxial curvature radius of an image-side surface of the fourthlens L4, r9: a paraxial curvature radius of an object-side surface ofthe fifth lens L5, and r10: a paraxial curvature radius of an image-sidesurface of the fifth lens L5.

It is not necessary to satisfy the above all conditional expressions,and by satisfying the conditional expression individually, operationaladvantage corresponding to each conditional expression can be obtained.

The imaging lens according to the present embodiments shows furtherpreferable effects by satisfying the following conditional expressions(1a) to (14a).14.50<vd2<25.00  (1a)0.25<|r5|/f<0.75  (2a)25.00<T3/T4<41.00  (3a)3.20<r8/f<29.00  (4a)−1.10<r10/f5<−0.50  (5a)−17.00<f2/T2<−8.00  (6a)46.00<vd4<66.00  (7a)0.50<(T4/f)×100<1.00  (8a)−13.50<r2/f<−2.50  (9a)0.55<r4/|r5|<1.60  (10a)6.50<|r5|/D3<23.00  (11a)−2.90<r7/T3<−1.00  (12a)2.50<|r9|/f<50.00  (13a)0.18<T2/T3<0.70  (14a)

The signs in the above conditional expressions have the same meanings asthose in the paragraph before the preceding paragraph.

In this embodiment, the aspheric shapes of the aspheric surfaces of thelens are expressed by Equation 1, where Z denotes an axis in the opticalaxis direction, H denotes a height perpendicular to the optical axis, Rdenotes a paraxial curvature radius, k denotes a conic constant, and A4,A6, A8, A10, Al2, A14, A16, A18 and A20 denote aspheric surfacecoefficients.

$\begin{matrix}{Z = {\frac{\frac{H^{2}}{R}}{1 + \sqrt{1 - {\left( {k + 1} \right)\frac{H^{2}}{R^{2}}}}} + {A_{4}H^{4}} + {A_{6}H^{6}} + {A_{8}H^{8}} + {A_{10}H^{10}} + {A_{12}H^{12}} + {A_{14}H^{14}} + {A_{16}H^{16}} + {A_{18}H^{18}} + {A_{20}H^{20}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Next, examples of the imaging lens according to this embodiment will beexplained. In each example, f denotes a focal length of the overalloptical system of the imaging lens, Fno denotes a F-number, ω denotes ahalf field of view, ih denotes a maximum image height, and TTL denotes atotal track length. Additionally, i denotes a surface number countedfrom the object side, r denotes a paraxial curvature radius, d denotes adistance of lenses along the optical axis (surface distance), Nd denotesa refractive index at d-ray (reference wavelength), and vd denotes anabbe number at d-ray. As for aspheric surfaces, an asterisk (*) is addedafter surface number i.

Example 1

The basic lens data is shown below in Table 1.

TABLE 1 Example 1 Unit mm f = 6.16 Fno = 2.40 ω(°) = 20.5 lh = 2.30 TTL= 5.41 Surface Data l r d Nd vd (Object) Infinity Infinity 1* 1.65261.1460 1.544 56.44 (vd1) 2* −39.2396 0.0500 3* 4.1333 0.2131 1.671 19.24(vd2) 4* 1.7733 0.4083 5* 2.6909 0.2752 1.535 55.69 (vd3) 6* 2.25610.2516 7 (Stop) Infinity 1.3384 8* −3.6555 0.2500 1.544 56.44 (vd4) 9*27.7912 0.0500 10* 109.3761 0.5558 1.671 19.24 (vdS) 11* −15.2247 0.570012 Infinity 0.2100 1.527 64.20 13 Infinity 0.1380 Image Plane InfinityConstituent Lens Data Lens Start Surface Focal Length 1 1 2.942 2 3−4.805 3 5 −33.498 4 8 −5.917 5 10 19.962 Aspheric Surface Data FirstSurface Second Surface Third Surface Fourth Surface Fifth Surface k−6.646973E−02  0.000000E+00  1.009354E+01  2.041238E+00  3.429719E+00 A4−1.279493E−03 −1.772276E−01 −3.826515E−01 −3.019833E−01  2.455909E−02 A6−4.367067E−03  8.078670E−01  1.294122E+00  8.781658E−01 −1.418966E−01 A8−1.479499E−03 −1.541302E+00 −2.171746E+00 −1.310578E+00  2.764525E+00A10  1.370126E−02  1.793777E+00  2.213581E+00  1.096692E+00−1.448690E+01 A12 −2.123532E−02 −1.394374E+00 −1.435801E+00−1.888393E−01  4.739405E+01 A14  1.431031E−02  7.234200E−01 5.481910E−01 −6.364503E−01 −1.015720E+02 A16 −4.564340E−03−2.393185E−01 −9.274960E−02  4.764885E−01  1.366712E+02 A18 4.454635E−04  4.544222E−02  0.000000E+00  0.000000E+00 −1.034618E+02A20  2.757876E−05 −3.753799E−03  0.000000E+00  0.000000E+10 3.358846E+01 Sixth Surface Eighth Surface Ninth Surface Tenth SurfaceEleventh Surface k  2.521151E+00  1.000000E+00  0.000000E+00 0.000000E+00 −1.485096E+01 A4  2.102001E−02  3.769455E−02  3.856033E−02−1.815181E−02 −1.078188E−01 A6  1.077126E+00 −1.351802E+00 −7.696161E−01 1.738714E−01  2.532646E−01 A8 −1.124340E+01  4.396305E+00  1.862517E+00−2.888283E−01 −2.876815E−01 A10  7.678719E+01 −8.122595E+00−2.499888E+00  2.601193E−01  2.099554E−01 A12 −3.158483E+02 9.442252E+00  2.020737E+00 −1.525916E−02 −1.045366E−01 A14 7.924994E+02 −6.929866E+00 −9.910531E−01  6.029420E−02  3.471095E−02A16 −1.189004E+03  3.102726E+00  2.848824E−01 −1.542756E−02−7.262131E−03 A18  9.830877E+02 −7.709675E−01 −4.337148E−02 2.279924E−03  8.578114E−04 A20 −3.443903E+02  8.127820E−02 2.625902E−03 −1.458647E−04 −4.331289E−05

The imaging lens in Example 1 satisfies conditional expressions (1) to(14) as shown in Table 6.

FIG. 2 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 1. The spherical aberration diagramshows the amount of aberration at each wavelength of F-ray (486 nm),d-ray (588 nm), and C-ray (656 nm). The astigmatism diagram shows theamount of aberration at d-ray on a sagittal image surface S (solid line)and on tangential image surface T (broken line), respectively (same asFIGS. 4, 6, 8 and 10 ). As shown in FIG. 2 , each aberration iscorrected excellently.

Example 2

The basic lens data is shown below in Table 2.

TABLE 2 Example 2 Unit mm f = 6.16 Fno = 2.40 ω(°) = 20.5 lh = 2.30 TTL= 5.38 Surface Data l r d Nd vd (Object) Infinity Infinity 1* 1.65301.1749 1.544 56.44 (vd1) 2* −42.1708 0.0500 3* 4.0554 0.2050 1.671 19.24(vd2) 4* 1.7733 0.4475 5* 2.2920 0.2435 1.535 55.69 (vd3) 6* 1.95730.2316 7 (Stop) Infinity 1.2989 8* −3.3191 0.2500 1.544 56.44 (vd4) 9*31.7415 0.0500 10* −52.8594 0.5690 1.671 19.24 (vdS) 11* −9.6020 0.570012 Infinity 0.2100 1.517 64.20 13 Infinity 0.1470 Image Plane InfinityConstituent Lens Data Lens Start Surface Focal Length 1 1 2.949 2 3−4.874 3 5 −33.669 4 8 −5.505 5 10 17.401 Aspheric Surface Data FirstSurface Second Surface Third Surface Fourth Surface Fifth Surface k−6.480485E−02  0.000000E+00  1.027997E+01  2.276312E+00  3.964667E+00 A4 1.431352E−04 −2.151818E−01 −4.917527E−01 −3.952282E−01 −1.567263E−01 A6−1.070032E−03  1.153999E+00  1.927668E+00  1.273035E+00  1.696603E+00 A8−8.983859E−03 −2.514969E+00 −3.826595E+00 −2.293328E+00 −9.767873E+00A10  3.065898E−02  3.208632E+09  4.519951E+00  2.625467E+00 4.327984E+01 A12 −4.386847E−02 −2.631999E+00 −3.222340E+00−1.573254E+00 −1.272452E+02 A14  3.218270E−02  1.406210E+00 1.287878E+00  2.358349E−01  2.427171E+02 A16 −1.303257E−02−4.732110E−01 −2.226277E−01  1.828490E−01 −2.875513E+02 A18 2.650715E−03  9.102676E−02  0.000000E+00  0.000000E+00  1.924545E+02A20 −2.109026E−04 −7.623070E−03  0.000000E−00  0.000000E+00−5.534147E+01 Sixth Surface Eighth Surface Ninth Surface Tenth SurfaceEleventh Surface k  2.163308E+00  1.300000E+00  0.000000E+00 0.000000E+00  2.615154E+00 A4 −3.499981E−01  1.045370E−01  1.604030E−01−3.495832E−02 −1.451308E−01 A6  7.943172E+00 −1.528510E+00 −1.269904E+00 2.303516E−01  3.323900E−01 A8 −9.004883E+01  3.922309E+00  2.837581E+00−3.849428E−01 −3.428872E−01 A10  6.444648E+02 −5.703973E+00−3.783236E+00  3.415730E−01  2.028760E−01 A12 −2.907466E−03 5.210279E+00  3.222745E+00 −1.827306E−01 −7.225022E−02 A14 8.293387E+03 −3.081948E+00 −1.759246E+00  6.062930E−02  1.502401E−02A16 −1.450877E+04  1.184658E+00  5.328849E−01 −1.227711E−02−1.603554E−03 A18  1.421067E+04 −2.752326E−01 −1.118251E−01 1.397772E−03  4.693553E−05 A20 −5.966595E+03  2.940462E−02 9.003601E−03 −6.879653E−05  3.397765E−06

The imaging lens in Example 2 satisfies conditional expressions (1) to(14) as shown in Table 6.

FIG. 4 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 2. As shown in FIG. 4 , eachaberration is corrected excellently.

Example 3

The basic lens data is shown below in Table 3.

TABLE 3 Example 3 Unit mm f = 7.20 Fno = 2.40 ω(°) = 15.8 lh = 2.04 TTL= 5.96 Surface Data l r d Nd vd (Object) Infinity Infinity 1 (Stop)Infinity −0.7041 2* 1.7054 1.0602 1.544 56.44 (vd1) 3* −21.3503 0.09274* 40.2179 0.2450 1.671 19.24 (vd2) 5* 5.0037 0.8171 6* −3.8854 0.28001.614 25.59 (vd3) 7* 22.2823 1.4853 8* −2.3356 0.2500 1.544 56.44 (vd4)9* 35.0265 0.0500 10* 178.4332 0.8836 1.671 19.24 (vdS) 11* −3.82100.2000 12 Infinity 0.1100 1.517 64.17 13 Infinity 0.5276 Image PlaneInfinity Constituent Lens Data Lens Start Surface Focal Length 1 2 2.9502 4 −8.544 3 6 −5.365 4 8 −4.012 5 10 5.588 Aspheric Surface Data SecondSurface Third Surface Fourth Surface Fifth Surface Sixth Surface k−4.850939E−02  0.000000E+00 −7.312651E+01 −4.314671E−01 −4.384112E+00 A4−2.074774E−02 −9.482573E−02 −1.208025E−01 −6.182821E−02  4.051087E−01 A6 7.913080E−02  6.673807E−01  1.186943E+00  1.029944E+00 −3.987298E+00 A8−2.274950E−01 −1.874500E+00 −3.899976E+00 −4.295451E+00  3.676441E+01A10  3.878194E−01  3.015009E+00  7.291539E+00  1.036908E+01−2.128845E+02 A12 −4.159997E−01 −3.051333E+00 −8.640035E+00−1.613155E+01  7.689337E+02 A14  2.811658E−01  1.974670E+00 6.542823E+00 −1.612926E+01 −1.746237E+03 A16 −1.161536E−01−7.933762E−01 −3.053439E+00 −9.973781E+00  2.422523E+03 A18 2.673424E−02  1.804851E−01  7.967645E−01  3.463098E+00 −1.875184E+03A20 −2.622695E−03 −1.779581E−02 −8.862201E−02 −5.154138E−01 6.205100E+02 Seventh Surface Eighth Surface Ninth Surface Tenth SurfaceEleventh Surface k −9.900000E+02  0.000000E+00  0.000000E+00 0.000000E+00  0.000000E+00 A4  3.052008E−01 −9.504369E−02 −5.957058E−02−7.557208E−04 −1.225162E−02 A6 −8.601368E−01  5.773480E−01  4.096163E−01 2.186796E−01  4.365035E−03 A8  4.552424E+00 −3.191782E+00 −2.153454E+00−1.085191E+00  2.375682E−02 A10 −1.263339E+01  9.355779E+00 4.752275E+00  2.110134E+00 −6.476608E−02 A12 −6.198741E−01−1.559865E+01 −5.693275E+00 −2.250712E+00  5.424030E−02 A14 1.015169E+02  1.543074E+01  3.992243E+00  1.419302E+00 −3.411045E−02A16 −2.766218E+02 −8.973000E+00 −1.636451E+00 −5.265518E−01 1.037508E−02 A18  3.195367E+02  2.831750E+00  3.628801E−01 1.060575E−01 −1.714236E−03 A20 −1.414236E+02 −3.734000E−01−3.358095E−02 −8.935539E−03  1.195948E−04

The imaging lens in Example 3 satisfies conditional expressions (1) to(14) as shown in Table 6.

FIG. 6 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 3. As shown in FIG. 6 , eachaberration is corrected excellently.

Example 4

The basic lens data is shown below in Table 4.

TABLE 4 Example 4 Unit mm f = 7.20 Fno = 2.40 ω(°) = 15.9 lh = 2.04 TTL= 5.96 Surface Data l r d Nd vd (Object) Infinity Infinity 1 (Stop)Infinity −0.7377 2* 1.6234 1.1056 1.544 56.44 (vd1) 3* −78.6361 0.20554* 17.8858 0.2472 1.671 19.24 (vd2) 5* 3.5346 0.5000 6* −4.6155 0.29871.614 25.59 (vd3) 7* 33.9433 1.6135 8* −2.2074 0.2500 56.44 (vd4) 9*31.2941 0.0500 1.544 10* 21.0559 0.8936 19.24 (vdS) 11* −4.2954 0.20001.671 12 Infinity 0.1100 64.17 13 Infinity 0.5268 1.517 Image PlaneInfinity Constituent Lens Data Lens Start Surface Focal Length 1 2 2.9362 4 −6.613 3 6 −6.595 4 8 −3.777 5 10 5.395 Aspheric Surface Data SecondSurface Third Surface Fourth Surface Fifth Surface Sixth Surface k−1.075000E−01  0.000000E+00  5.500000E+01  3.630358E−01  2.408069E+00 A4−1.603799E−02  1.821507E−02  4.084822E−02 −5.037554E−02  3.317309E−01 A6 8.900601E−02  9.602220E−02  5.881615E−01  2.025986E+00 −1.931605E+00 A8−2.739078E−01 −4.400012E−01 −3.468075E+00 −1.255793E+01  1.223334E+01A10  4.864424E−01  8.718801E−01  9.896230E+00  4.393990E+01−5.223115E+01 A12 −5.307375E−01 −1.039878E+00 −1.741746E+01−9.695547E+01  1.395239E+02 A14  3.600739E−01  7.753300E−01 1.930927E+01  1.355990E+02 −2.352046E+02 A16 −1.482423E−01−3.530081E−01 −1.305997E+01 −1.164050E+02  2.420051E+02 A18 3.385528E−02  8.987299E−02  4.921260E+00  5.599602E+01 −1.376945E+02A20 −3.301692E−03 −9.825551E−03 −7.928041E−01 −1.157789E+01 3.268000E+01 Seventh Surface Eighth Surface Ninth Surface Tenth SurfaceEleventh Surface k  0.300000E+00  0.000000E+00  0.000000E+00 0.000000E+00  0.000000E+00 A4  5.187744E−01  4.584798E−02  1.879454E−01 1.003143E−01 −2.106187E−02 A6 −5.042962E+00 −1.242617E−01 −9.420195E−01−5.321352E−01 −3.315378E−02 A8  4.344217E+01 −6.414054E−01  1.398945E+00 7.587927E−01  8.542177E−02 A10 −2.251445E+02  3.530708E+00−6.509205E−01 −3.502550E−01 −1.126688E−01 A12  7.126549E+02−7.401690E+00 −5.576748E−01 −2.205426E−01  9.154002E−02 A14−1.337123E+03  8.332558E+00  3.878456E−01  3.475509E−01 −4.617117E−02A16  1.376636E+03 −5.286844E+00 −4.770879E−01 −1.734871E−01 1.386821E−02 A18 −6.045640E+02  1.775020E+00  1.193043E−01 4.009131E−02 −2.258348E−03 A20  9.180000E+00 −2.443000E−01−1.160371E−02 −3.614608E−03  1.529652E−04

The imaging lens in Example 4 satisfies conditional expressions (1) to(14) as shown in Table 6.

FIG. 8 shows spherical aberration (mm), astigmatism (mm), and distortion(%) of the imaging lens in Example 4. As shown in FIG. 8 , eachaberration is corrected excellently.

Example 5

The basic lens data is shown below in Table 5.

TABLE 5 Example 5 Unit mm f = 7.20 Fno = 2.40 ω(°) = 16.0 lh = 2.04 TTL= 5.96 Surface Data l r d Nd vd (Object) Infinity Infinity 1 (Stop)Infinity −0.7367 2* 1.6326 1.0974 1.544 56.44 (vd1) 3* −48.6508 0.20504* 22.5536 0.2496 1.671 19.24 (vd2) 5* 3.7549 0.5000 6* −4.3075 0.29791.614 25.59 (vd3) 7* 42.8455 1.6213 8* −2.2410 0.2500 1.544 56.44 (vd4)9* 165.3714 0.0500 10* 49.8108 0.8927 1.671 19.24 (vdS) 11* −4.13470.2000 12 Infinity 0.1100 1.517 64.17 13 Infinity 0.5257 Image PlaneInfinity Constituent Lens Data Lens Start Surface Focal Length 1 2 2.9242 4 −6.752 3 6 −6.357 4 8 −4.059 5 10 5.731 Aspheric Surface Data SecondSurface Third Surface Fourth Surface Fifth Surface Sixth Surface k−1.404541E−01  0.000000E+00  2.641489E+02  1.564142E+00 −9.950852E−01 A4−1.203901E−02  3.394558E−02  7.371014E−02 −2.513409E−02  3.367861E−01 A6 7.918856E−02  5.007861E−02  4.707908E−01  1.891094E+00 −1.967334E+00 A8−2.553516E−01 −4.165866E−01 −3.471478E+00 −1.241728E+01  1.279863E+01A10  4.675312E−01  9.623321E−01  1.069653E+01  4.446775E+01−5.698635E+01 A12 −5.233542E−01 −1.232269E+00 −1.936586E+01−9.843845E+01  1.617984E+02 A14  3.633341E−01  9.514130E−01 2.159841E+01  1.368194E+02 −2.942460E+02 A16 −1.527004E−01−4.407782E−01 −1.456078E+01 −1.163017E+02  3.308428E+02 A18 3.550857E−02  1.131481E−01  5.450707E+00  5.536365E+01 −2.084806E+02A20 −3.517238E−03 −1.240644E−02 −8.716155E−01 −1.133963E+01 5.585444E+01 Seventh Surface Eighth Surface Ninth Surface Tenth SurfaceEleventh Surface k  0.000000E+02  0.000000E+00  0.000000E+00 0.000000E+00  0.000000E+00 A4  5.242605E−01  6.090194E−02  2.142377E−01 1.027797E−01 −2.788012E−02 A6 −5.439702E+00 −2.937105E−01 −9.711624E−01−4.437229E−01 −7.761265E−03 A8  5.233420E+01  1.612716E−01  1.477360E+00 5.024013E−01  4.812177E−02 A10 −3.076243E+02  1.367569E+00−9.152200E−01 −1.100272E−02 −8.137479E−02 A12  1.124260E+03−3.860242E+00 −1.310929E−01 −4.846704E−01  7.461064E−02 A14−2.563585E+03  4.771726E+00  5.245585E−01  4.760663E−01 −4.051055E−02A16  3.527459E+03 −3.153347E+00 −3.058168E−01 −2.116720E−01 1.296352E−02 A18 −2.660583E+03  1.079200E+00  7.684529E−02 4.635806E−02 −2.197069E−03 A20  8.355021E+02 −1.495000E−01−7.250000E−03 −4.044044E−03  1.553382E−04

The imaging lens in Example 5 satisfies conditional expressions (1) to(14) as shown in Table 6.

FIG. 10 shows spherical aberration (mm), astigmatism (mm), anddistortion (%) of the imaging lens in Example 5. As shown in FIG. 10 ,each aberration is corrected excellently.

In table 6, values of conditional expressions (1) to (14) related to theExamples 1 to 5 are shown.

TABLE 6 Conditional Exam- Exam- Exam- Exam- Exam- Expressions ple 1 ple2 ple 3 ple 4 ple 5 (1) vd2 19.24 19.24 19.24 19.24 19.24 (2) |r5|/f0.44 0.37 0.54 0.64 0.60 (3) T3/T4 31.80 30.61 29.71 32.27 32.43 (4)r8/f 4.51 5.15 4.86 4.34 22.96 (5) r10/f5 −0.76 −0.55 −0.68 −0.80 −0.72(6) f2/T2 −11.77 −10.89 −10.46 −13.23 −13.50 (7) vd4 56.44 56.44 56.4456.44 56.44 (8) (T4/f) × 100 0.81 0.81 0.69 0.69 0.69 (9) r2/f −6.37−6.85 −2.96 −10.92 −6.75 (10) r4/|r5| 0.66 0.77 1.29 0.77 0.87 (11)|r5|/D3 9.78 9.41 13.88 15.45 14.46 (12) r7/T3 −2.30 −2.17 −1.57 −1.37−1.38 (13) |r9|/f 17.76 8.58 24.77 2.92 6.93 (14) T2/T3 0.26 0.29 0.550.31 0.31

When the imaging lens according to the present invention is adopted to aproduct with the camera function, there is realized contribution tolow-profileness and low F-number of the camera and also high performancethereof.

DESCRIPTION OF REFERENCE NUMERALS

-   ST: aperture stop-   L1: first lens-   L2: second lens-   L3: third lens-   L4: fourth lens-   L5: fifth lens-   ih: maximum image height-   IR: filter-   IMG: imaging plane

What is claimed is:
 1. An imaging lens comprising in order from anobject side to an image side, a first lens with positive refractivepower formed in a biconvex shape having an object-side surface and animage-side surface being convex in a paraxial region, a second lens withnegative refractive power in a paraxial region, a third lens with thenegative refractive power in a paraxial region, a fourth lens with thenegative refractive power in a paraxial region, and a fifth lens withthe positive refractive power having an image-side surface being convexin a paraxial region, wherein the following conditional expressions (1),(2), and (3) are satisfied:10.00<vd2<30.00  (1)0.10<|r5|/f<0.90  (2)20.50<T3/T4<49.00  (3) where vd2: an abbe number at d-ray of the secondlens, r5: a paraxial curvature radius of an object-side surface of thethird lens, f: a focal length of the overall optical system of theimaging lens, T3: a distance along an optical axis from an image-sidesurface of the third lens to an object-side surface of the fourth lens,and T4: a distance along an optical axis from an image-side surface ofthe fourth lens to an object-side surface of the fifth lens.
 2. Theimaging lens according to claim 1, wherein an object-side surface ofsaid second lens is convex in the paraxial region.
 3. The imaging lensaccording to claim 1, wherein an image-side surface of said third lensis concave in the paraxial region.
 4. The imaging lens according toclaim 1, wherein the following conditional expression (4) is satisfied:2.00<r8/f<35.00  (4) where r8: a paraxial curvature radius of animage-side surface of the fourth lens, and f: a focal length of theoverall optical system of the imaging lens.
 5. The imaging lensaccording to claim 1, wherein the following conditional expression (5)is satisfied:−1.40<r10/f5<−0.40  (5) where r10: a paraxial curvature radius of animage-side surface of the fifth lens, and f5: a focal length of thefifth lens.
 6. The imaging lens according to claim 1, wherein thefollowing conditional expression (6) is satisfied:−20.00<f2/T2<−5.50  (6) where f2: a focal length of the second lens, andT2: a distance along an optical axis from an image-side surface of thesecond lens to an object-side surface of the third lens.
 7. An imaginglens comprising in order from an object side to an image side, a firstlens with positive refractive power formed in a biconvex shape having anobject-side surface and an image-side surface being convex in a paraxialregion, a second lens with negative refractive power in a paraxialregion, a third lens with the negative refractive power in a paraxialregion, a fourth lens with the negative refractive power in a paraxialregion, and a fifth lens with the positive refractive power having animage-side surface being convex in a paraxial region, wherein thefollowing conditional expressions (1), (2) and (4) are satisfied:10.00<vd2<30.00  (1)0.10|r5|/f<0.90  (2)2.00<r8/f<35.00  (4) where vd2: an abbe number at d-ray of the secondlens, r5: a paraxial curvature radius of an object-side surface of thethird lens, r8: a paraxial curvature radius of an image-side surface ofthe fourth lens, and f: a focal length of the overall optical system ofthe imaging lens.